Provide alternative SDL audio output

CMakeLists.txt

@@ -36,7 +36,7 @@ if(FREESCALE_FOUND)
 endif()
 
 if (AVCODEC_FOUND AND AVUTIL_FOUND AND SWSCALE_FOUND AND SDL_FOUND)
-  list(APPEND SRC_LIST ./src/video/ffmpeg.c ./src/video/sdl.c)
+  list(APPEND SRC_LIST ./src/video/ffmpeg.c ./src/video/sdl.c ./src/audio/sdl.c)
   list(APPEND MOONLIGHT_DEFINITIONS HAVE_SDL)
 endif()
 

src/audio.h

@@ -22,3 +22,6 @@
 extern const char* audio_device;
 
 extern AUDIO_RENDERER_CALLBACKS audio_callbacks_alsa;
+#ifdef HAVE_SDL
+extern AUDIO_RENDERER_CALLBACKS audio_callbacks_sdl;
+#endif

src/audio/sdl.c

@@ -0,0 +1,79 @@
+/*
+ * This file is part of Moonlight Embedded.
+ *
+ * Copyright (C) 2015 Iwan Timmer
+ *
+ * Moonlight is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Moonlight is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Moonlight; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "../audio.h"
+
+#include <SDL.h>
+#include <SDL_audio.h>
+
+#include <stdio.h>
+#include <opus.h>
+
+#define SAMPLE_RATE 48000
+#define CHANNEL_COUNT 2
+#define FRAME_SIZE 240
+
+static OpusDecoder* decoder;
+static short pcmBuffer[FRAME_SIZE * CHANNEL_COUNT];
+static SDL_AudioDeviceID dev;
+
+static void sdl_renderer_init() {
+  int rc;
+  decoder = opus_decoder_create(SAMPLE_RATE, CHANNEL_COUNT, &rc);
+
+  SDL_InitSubSystem(SDL_INIT_AUDIO);
+
+  SDL_AudioSpec want, have;
+  SDL_zero(want);
+  want.freq = SAMPLE_RATE;
+  want.format = AUDIO_S16LSB;
+  want.channels = CHANNEL_COUNT;
+  want.samples = 4096;
+
+  dev = SDL_OpenAudioDevice(NULL, 0, &want, &have, SDL_AUDIO_ALLOW_FORMAT_CHANGE);
+  if (dev == 0) {
+    printf("Failed to open audio: %s\n", SDL_GetError());
+  } else {
+    if (have.format != want.format)  // we let this one thing change.
+      printf("We didn't get requested audio format.\n");
+    SDL_PauseAudioDevice(dev, 0);  // start audio playing.
+  }
+}
+
+static void sdl_renderer_cleanup() {
+  if (decoder != NULL)
+    opus_decoder_destroy(decoder);
+
+  SDL_CloseAudioDevice(dev);
+}
+
+static void sdl_renderer_decode_and_play_sample(char* data, int length) {
+  int decodeLen = opus_decode(decoder, data, length, pcmBuffer, FRAME_SIZE, 0);
+  if (decodeLen > 0) {
+    SDL_QueueAudio(dev, pcmBuffer, decodeLen * CHANNEL_COUNT * sizeof(short));
+  } else {
+    printf("Opus error from decode: %d\n", decodeLen);
+  }
+}
+
+AUDIO_RENDERER_CALLBACKS audio_callbacks_sdl = {
+  .init = sdl_renderer_init,
+  .cleanup = sdl_renderer_cleanup,
+  .decodeAndPlaySample = sdl_renderer_decode_and_play_sample,
+};

src/platform.c

@@ -72,6 +72,10 @@ DECODER_RENDERER_CALLBACKS* platform_get_video(enum platform system) {
 
 AUDIO_RENDERER_CALLBACKS* platform_get_audio(enum platform system) {
   switch (system) {
+  #ifdef HAVE_SDL
+  case SDL:
+    return &audio_callbacks_sdl;
+  #endif
   default:
     return &audio_callbacks_alsa;
   }